Leak-proof dispensing pump

Abstract

A dispensing pump having a unitary plunger defining a main pump chamber and functioning as a discharge valve upon accumulation of pressure causing the plunger to shift open, includes a container vent which is positively sealed against leakage therethrough even upon nudging the plunger during storage, shipment and handling of the pump. The pump includes a fixed position and a reciprocable plunger head having a discharge passage, the inside of the head and the top of the piston being complementarily contoured for expelling accumulated air from the pump chamber directly out of the discharge during priming. Otherwise, the pump chamber may be placed in communication with a vent chamber which opens into the container through the vent so that any accumulated air in the pump chamber may be vented into the container as an aid in priming. The volume beneath the plunger head may be enclosed as an air chamber so that the air therein may be vented into the container upon opening the container vent to assist in pump priming. And, the plunger is designed to effect a quick or a slow opening of the discharge passage.

What is claimed is: 
     
       1. In a liquid dispenser comprising a pump body sealingly mounted on a container of flowable product to be dispensed, said body having a container vent opening therein and a stationary piston thereon, an annular plunger resiliently urged into a fully raised position and mounted for reciprocation on said piston to define therewith a variable volume pump chamber, a valve controlled inlet passage in said piston, a plunger head slidably disposed on said plunger and having a discharge passage adapted to be opened and closed by said plunger upon an increase in pressure within said chamber, the improvement wherein means are provided for opening and closing said vent opening upon reciprocation of said plunger, said means comprising a vertical first cylindrical wall spaced from and surrounding said piston so as to therewith define a vent chamber which is in open communication with the interior of the container via said vent opening, means defining a container vent passage extending from the interior of the container via said vent opening and said open vent chamber, outwardly of said plunger and outwardly of said plunger head, said opening and closing means further comprising skirt means on said plunger in sealing engagement with an inner surface of said wall for closing said vent passage while said plunger is in its raised position and during an initial downstroke reciprocation thereof, said skirt means being further adapted to open said vent passage upon a further downstroke reciprocation of said plunger, whereby the interior of the container is vented to atmosphere only during said further downstroke reciprocation, and any leakage of product from the container through said vent passage is positively prevented while said plunger is in said raised position and during said initial downstroke.   
     
     
       2. In the dispenser according to claim 1, wherein said vent opening is located in said cylindrical wall at a lower portion thereof for establishing communication between the interior of the container and the atmosphere upon said further downstroke reciprocation of said plunger. 
     
     
       3. In the dispenser according to claim 1, wherein said wall has an enlarged lower portion defining a gap with said skirt means during said further downstroke reciprocation, said gap defining a portion of said passage. 
     
     
       4. In the dispenser according to claim 3, wherein said inner surface of said wall has a first predetermined diameter at an upper portion thereof for establishing the sealing engagement with said skirt means, and said lower portion at its lower end having a second large predetermined diameter with said surface smoothly tapering between said diameters, whereby said vent passage is gradually opened between said diameters during the downstroke reciprocation. 
     
     
       5. In the dispenser according to claim 3, wherein said inner surface of said wall has a first predetermined diameter at an upper portion thereof for establishing the sealing engagement with said skirt means, and the remainder of said inner surface has a second, larger and constant predetermined diameter. 
     
     
       6. In the dispenser according to claims 1, 2, 3, 4 or 5, wherein the upper end of said piston and an opposing inner surface of said plunger head are complementarily contoured so that the pump may be effectively primed as any air within said pump chamber is substantially evacuated through said discharge passage upon depressing said head. 
     
     
       7. In the dispenser according to claims 1, 2, 3, 4 or 5, wherein means are provided at an upper inner end of said plunger for establishing communication between said pump chamber and said vent chamber near the end of the downstroke reciprocation upon contact between said piston and said establishing means, whereby the dispenser may be primed as any air within said pump chamber is compressed before said vent is opened and is substantially evacuated into the container under compression at the time said vent is opened to thereby boost the product within the container to serve as an aid in priming. 
     
     
       8. In the dispenser according to claim 7, wherein said establishing means comprises a first axial rib and said piston includes an annular lip seal of resilient material at the upper end thereof, whereby said lip seal is distorted upon contact with said rib during relative reciprocating movement between said plunger and said piston. 
     
     
       9. In the dispenser according to claim 1, wherein said vent is located in said cylindrical wall between opposite ends thereof, means being provided on an upper inner end of said plunger and on a lower inner end of said wall below said vent opening for establishing communication between said pump chamber and said vent chamber near the end of the downstroke reciprocation upon contact between said establishing means and said piston and between said establishing means and said skirt means, whereby the dispenser may be primed as any air within said pump chamber is compressed before said vent is opened and is substantially evacuated into said container under compression at the time said vent is opened to thereby boost the product within the container to serve as an aid in priming. 
     
     
       10. In the dispenser according to claim 9, wherein said establishing means comprise axial ribs, the upper end of said piston and said skirt means defining annular lip seals of resilient material, whereby said lip seals are distorted upon contact with said ribs during relative reciprocating movement between said plunger and said piston. 
     
     
       11. In the pump according to claims 1, 2, 3, 4 or 5, wherein means for priming the pump comprise a variable volume air chamber defined by a piston wall portion on said head spaced from said plunger and a cylindrical wall portion on said body spaced from said first wall, annular cooperating stop shoulders on said wall portions for arresting the upward movement of said head, and means at a lower inner end of said cylindrical wall portion for opening said air chamber to atmosphere, whereby upon depressing said head the air within said air chamber is compressed before said vent is opened to thereby boost the product within the container when said vent is opened to serve as an aid in priming, said means at said lower inner end establishing said vent passage when said head nears the end of the downstroke. 
     
     
       12. In the dispenser according to claim 11, wherein said stop shoulder on said piston wall is of resilient material, and sealingly engages an inner surface of said cylindrical wall portion, and said means on said inner end comprising an axial rib, said vent passage thereby established upon distortion of said piston wall stop shoulder when contacting said rib. 
     
     
       13. In the dispenser according to claim 7, wherein additional means for priming the pump comprise a variable volume air chamber defined by a piston wall portion on said head spaced from said plunger and a cylindrical wall portion on said body spaced from said first wall, annular cooperating stop shoulders on said wall portions for arresting the upward movement of said head, and means at a lower inner end of said cylindrical wall portion for opening said air chamber to atmosphere, whereby upon depressing said head the air within said air chamber is compressed before said vent is opened to thereby boost the product within the container when said vent is opened to serve as an aid in priming, said means at said lower inner end establishing said vent passage when said head nears the end of the downstroke. 
     
     
       14. In the dispenseer according to claims 1, 2, 3, 4 or 5, wherein said head has a downwardly directed blind socket so as to define with said plunger a variable volume accumulation chamber between said plunger and the blind end of said socket and being in open communication with said pump chamber, said discharge passage being opened and closed by relative movement between said head and said plunger, said blind socket including an annular ring depending from the top of said head, the upper end of said plunger having an annular groove engaging said ring and defining an annular discharge valve flange, said flange having a terminal end lying above said discharge passage so as to define a slow acting discharge valve. 
     
     
       15. In the dispenser according to claims 1, 2, 3, 4 or 5, wherein said head has a downwardly directed blind socket so as to define with said plunger a variable volume accumulation chamber between said plunger and the blind end of said socket and being in open communication with said pump chamber, said discharge passage being opened and closed by relative movement between said head and said plunger, said blind socket including an annular ring depending from the top of said head, the upper end of said plunger having an annular groove engaging said ring and defining an annular discharge valve flange, said flange having a terminal end lying below said discharge passage so as to define a quick acting discharge valve.